Thread by @federicolois

1/ Let me dispel some myths caused by credentialism statements like: "Trust me, I am a surgeon and I been doing this for decades".

First, there is evidence that they don't even work in the operating room.

https://twitter.com/JohnRTMonsonMD/status/1595893878879551489

2/ Let's start with the basics. Ritter et al. [1975] “the wearing of a surgical face mask had no effect upon the overall operating room environmental contamination.” Oops.
pubmed.ncbi.nlm.nih.gov/1157412/

3/ Ha’eri and Wiley [1980] they used albumin microspheres to the interior of the mask (source control) and they look for them in the OR and operating field. “Particle contamination of the wound was demonstrated in all experiments.” Mhhh.
europepmc.org/article/med/73…

4/ Laslett and Sabin [1989] “No infections were found in any patient, regardless of whether a cap or mask was used” onlinelibrary.wiley.com/doi/abs/10.100…
Bonus track: Sjøl and Kelbaek [2002] europepmc.org/article/med/11…

5/ Tunevall [1991] 1,537 surgeries with masks, infections in 4.7%. 1,551 surgeries without masks, infections in 3.5%. Double Oops!!!
link.springer.com/article/10.100…

6/ Skinner and Sutton [2001] “The evidence for discontinuing the use of surgical face masks would appear to be stronger than the evidence available to support their continued use.”
journals.sagepub.com/doi/pdf/10.117…

7/ Lahme et al [2001] “surgical face masks worn by patients during regional anesthesia, did not reduce the concentration of airborne bacteria over the operation field in our study. Thus they are dispensable.”
europepmc.org/article/med/11…

8/ Figueiredo et al. [2001] 5 years of peritoneal dialisis without face masks. Peritonitis rates at the unit no different than the ones found in hospitals that used face masks. advancesinpd.com/adv01/21Figuei…
Should I continue?

9/ Why shouldn't I, since there are so many more. Bahli [2009] “no significant difference in the incidence of postoperative wound infection was observed between masks groups and groups operated with no masks.”
semanticscholar.org/paper/Does-evi…

10/ Karolinska Institute [2010] “Our decision to no longer require routine surgical masks for personnel not scrubbed for surgery is a departure from common practice. But the evidence to support this practice does not exist,” wrote Dr. Eva Sellden.
pubs.asahq.org/anesthesiology…

11/ I don't want to bore you, but there is so much more. That is without even starting with pro-mask studies like the Syrian Hamsters that paradoxically show that the critters with higher viral load in the lungs are the masked ones.

https://twitter.com/federicolois/status/1358170634107424771

12/ Or aerosol exposure may lead to more severe illness. Triple Oops!!!

https://twitter.com/contrarian4data/status/1405277051733483521

I understand MDs have lots of fluid and particulate dynamics classes about the physics of airborne particles in the nasopharynx.

13/ That is of-course without considering harms. Including potential exposure to carcinogenic substances.

https://twitter.com/federicolois/status/1563387040540274688

14/ When someone, no matter how "credentialed", talks without evidence it is our duty to call BS on it. You know in the old age, they had been burning witches for ages until we realized that maybe it was not such a good idea. via @bobscartoons